Interpretive Summary: The South American weed tropical soda apple (TSA) was found in Florida in 1988. TSA invades pastures and has become a pest throughout the southeastern U.S. from Texas to the Carolinas. Scientists with USDA-ARS Center for Medical, Agricultural and Veterinary Entomology in Tallahassee, FL, along with the Florida Department of Agriculture and University researchers from Florida and Brazil, introduced a leaf-feeding beetle from Argentina in 2003 that eats nothing but TSA. Thousands of these beetles have been reared and released across Florida. At most locations the beetles have become established and are causing extensive defoliation and fruit loss of attacked TSA plants. The beetles have spread on their own, as much as 10 miles/year. Since these beetles do not feed on any plants except TSA and they are negatively impacting TSA, additional releases and dispersal of the beetles will continue in Florida in an effort to control populations of TSA.

Technical Abstract:
Solanum viarum Dunal (Solanaceae) is an invasive perennial shrub in southeastern USA. Native to South America, it was first found in Florida in 1988, and it has already invaded more than 400,000 ha of grasslands and conservation areas in 11 states. Currently recommended control tactics for this weed in pastures are based on herbicide applications combined with mechanical (mowing) practices. These control tactics provide a temporary solution and can cost as much as $188/ha for dense infestations of the weed. A biological control project against S. viarum was initiated in 1997. After 3 years of intensive host-specificity testing, the South American leaf beetle Gratiana boliviana was approved for field release by the United States Department of Agriculture (USDA) – Animal and Plant Health Inspection Service (APHIS) – Plant Protection and Quarantine (PPQ) in 2003, and its release in Florida began in summer 2003. Up to now, approximately 120,000 beetles have been released in 25 counties in Florida. The beetles established at virtually all the release sites in Florida. Beetle dispersal has been based on plant availability with annual dispersal from 1.6 to 16km/yr from the release sites. Initial impacts of the beetles range from 30% to 100% plant defoliation. The fruit production declined from 40 to 55 fruits per plant in summer 2003, when beetles were released, to zero or a few deformed fruits (one to four per plant) 2 years post release in five of the release sites monitored. Mass rearing, field release and post-release evaluation of G. boliviana and the target plant will continue during 2008.